Question

A ${{Si}}$ and a ${{Ge}}$ diode has identical physical dimensions. The band gap in ${{Si}}$ is larger than that in ${{Ge}}$. An identical reverse bias is applied across the diodes.
A. The reverse current in ${{Ge}}$ is larger than that in ${{Si}}$.
B. The reverse current in ${{Si}}$ is larger than that in ${{Ge}}$.
C. The reverse current is identical in the two diodes.
D. The relative magnitude of the reverse currents cannot be determined from the given data only.

Answer 1

Hint: Semi-conductor has properties between conductors and insulators. There are two types of semi-conductors. They are intrinsic and extrinsic semi-conductors. They have a smaller energy gap between bands than insulators. They have negative and positive charge carriers.

Complete step by step answer:
Diode is an electric device which allows current to flow only in one direction. Silicon and Germanium are the two most common single elements that are used to make diodes. Diodes are formed by joining p-type and n-type semiconductor. When a small amount of pentavalent impurity is added to a pure semi-conductor, it is known as n-type semi-conductor. When a small amount of trivalent impurity is added to a pure semi-conductor, it is called p-type semi-conductor.
The voltage applied to the semi-conductor diode is referred to as bias voltage. When voltage is applied across a diode in such a way that the diode prohibits current and potential barrier increase, the diode is said to be reverse biased. The polarity of applied voltage which cannot produce any current is called reverse bias. Under reverse bias, the depletion region becomes wider after fully stopping the current through the diode.
When a p-n junction is reverse biased, the current through the junction is due to electrons in p and holes in n section. The concentration of these carriers depends upon the energy gap. Since silicon has a greater band gap than germanium, silicon needs higher forward bias voltage for conduction than germanium. When we apply reverse bias voltage, there is a slight leakage current which is constant. Silicon and germanium have the same physical dimensions. Thus the reverse saturation current will be identical.

So, the correct answer is Option C.

Note: The polarity of applied voltage which cannot produce any current is called reverse bias. Under reverse bias, the depletion region becomes wider after fully stopping the current through the diode. Under reverse bias, the depletion region becomes wider after fully stopping the current through the diode.